JPH04356437A - Method for converting tertiary amine n-oxide into aldehyde - Google Patents

Abstract

Process for the conversion of N-oxides of tertiary amines to aldehydes by means of a catalyst derived from vanadium, as well as the preparation of unsaturated aldehydes from dienes.

Description

[Detailed description of the invention]

This invention relates to the conversion of N-oxides, and more particularly to the conversion of tertiary amine N-oxides to aldehydes.

It is known that N-oxides of tertiary amines containing at least one methyl group are converted into secondary amines and formaldehyde in the presence of excess acetic anhydride (Polonowsky). reaction)
.

[0003] The use of this reaction for the synthesis of terpenes (Takabe et al., Synthetic Commun
cations, 13(4) 297-301,
(1983)), more precisely for the production of citral from the N-oxide of N-dialkylgeranylamine (U.S. Pat. No. 4,447,649).
is also known.

However, this type of reaction consumes acetic anhydride and, furthermore, the secondary amine cannot be recycled. These two drawbacks pose considerable obstacles to its application on an industrial level.

In an effort to overcome these drawbacks, other conversion reagents have been used instead of acetic anhydride, such as especially M
nO2 (Henbest et al., Amine Oxydat
ion part I, 3035, (1957)),
SO2 (Lecher et al., J. Am. Chem.
Soc. 70, 3789, (1948)) or various metal salts. F for the rearrangement of N-oxides in the presence of ferric ions
ish et al. (J. Am. Chem. Soc. 78
, 3668, (1956)) may be mentioned in particular.

Finally, Ferris et al. (J. Org.
Chem. 33, 3493, (1968)) and Craig et al. (J. Am. Chem. Soc.
．． 83, 1871, (1961)) showed the possibility of using metals other than iron, especially transition metals such as ruthenium, osmium and vanadium. However, for this last one, trimethylamine N-
Only activities related to oxide conversion were exemplified. In addition, this reaction produces very large amounts of transition metal compounds,
It is carried out only in a very dilute aqueous medium in the presence of VOCl2 (3 times as much as the N-oxide, which cannot be considered as a catalyst), and furthermore this results in the formation of formic acid. . Under these conditions, apart from average yields, high consumption of metal derivatives, very high acidity of the reaction medium (pH 1.
5) and the high degree of dilution, it is unlikely that this method can be easily scaled up on an industrial scale.

By treatment in the presence of catalytic amounts of one or more vanadium derivatives, it is possible to convert N-oxides of tertiary amines into aldehydes and secondary amines in high yields. We have discovered something, and this is the subject of the present invention. The method of the present invention has the advantage that it does not generate acids and it is possible to easily recover the secondary amine. This method can also be carried out under very favorable pH and temperature conditions.

Accordingly, the present invention provides a method for converting the N-oxide of a tertiary amine to an aldehyde, comprising contacting the N-oxide with a catalytic amount of one or more vanadium derivatives. As used herein, the term "catalytic amount" means that the molar ratio of vanadium derivative (calculated as metal)/N-oxide is less than 1.

[0009] Advantageously, the process of the invention is carried out in the presence of a solvent.

The N-oxides of tertiary amines used in the present invention can be obtained by oxidizing the corresponding amines with an oxidizing agent. Specifically, U.S. Patent No. 4,
247,480, it is possible to use hydrogen peroxide alone or under carbon dioxide pressure.

[0011] In detail, the N-oxides of tertiary amines that can be used in the present invention have the general formula:

0012

[Case 2]

[In the formula, each of R1, R2 and R3 is
linear, branched or cyclic alkyl, alkenyl or benzyl groups, which may be the same or different and which may be substituted or unsubstituted and have up to 30 carbon atoms and optionally one or more heteroatoms; and R1 and R2 may be taken together to form a ring].

Advantageously, R1 and R2 are a linear or branched alkyl group, which may be the same or different and each have 1 to 4 carbon atoms, and together form a carbocyclic or heterocyclic group. may form a formula ring. More advantageously, R1 and R2, which may be the same or different, each represent methyl or ethyl.

Most preferably, in formula (I), R3 is a substituted or unsubstituted linear group having from 3 to 30 carbon atoms optionally having a ring and/or one or more heteroatoms. Or it is a branched allyl group.

Preferably, in formula (I), R3 is substituted or unsubstituted benzyl having up to 30 carbon atoms. In particular, the benzyl system is substituted with an alkyl, alkenyl, acyl, alkoxy or hydroxyl group or has the formula CHO, -R4-COO
has a group of R5 or -R4-X (wherein, R4 represents a valence bond or a divalent hydrocarbon group, R5 represents a hydrogen atom or an alkyl group, and X represents a halogen atom); You can.

Preferably, R3 is an allyl group having 3 to 15 carbon atoms or a benzyl group optionally substituted on the aromatic ring.

More preferably, the N-oxide of formula (I) is N,N-dialkylprenylamine N-oxide, N-oxide of N,N-dialkylgeranylamine, or its isomer N,N - dialkylnerylamine N-oxide, N,N-dialkylbenzylamine N-oxide, or N,N-dialkyl-(2
,6,6-trimethyl-1-cyclohexyl)methanamine N-oxide. In this context, the term "geranylamine" means a mixture of isomeric geranyl- and neryl-amines.

Vanadium derivatives which can be used in particular in the process of the invention may be salts of vanadium in any possible oxidation state. In the highly oxidized state, especially V2O5,
NH4VO3 and alkyl vanadates such as triethanolamine orthovanadate (OVTEA) and octadecyl orthovanadate (OV (OC18
H37)3) (oxidation number 5), and acetylacetone vanadyl (OV(AcAc)2) or vanadyl sulfate (VOSO4) (oxidation number 4).

These vanadium derivatives may be used in suspension or on a support. In the latter case, oxidized type supports may be used, such as in particular alumina or silica. Charcoal or resin can also be used.

In a preferred embodiment of the process of the invention, the amount of vanadium catalyst is such that the molar ratio of vanadium derivative (calculated as metal)/N-oxide is between 0.0001 and 0.
．． 5, preferably in an amount between 0.001 and 0.1.

Regarding solvents, the process may be carried out using hydrocarbons, ethers, esters, alcohols, aromatic solvents or halogenated solvents. Hydrocarbons include pentane or hexane, esters include ethyl acetate, ethers include methyl tert-butyl ether, halogenated solvents include methylene chloride or chlorobenzene, and aromatic solvents include toluene, xylene or benzene. and methanol as an alcoholic solvent; however, this list is of course not limited to this.

The pH of the reaction medium is advantageously adjusted by adding acids, which may be organic or inorganic or both. In particular, it is also possible to use acids such as acetic acid, benzoic acid, tartaric acid, formic acid or crotonic acid alone or together with inorganic acids such as hydrochloric acid or sulfuric acid in addition to the pH adjusted with organic acids. Preferably, carboxylic acids are used. The pH of this medium is preferably adjusted to a value between 4 and 7.

In a preferred embodiment of the invention, the reaction medium comprises 0.05 to 2 liters of water and 0 to 20 liters, preferably 0.5 to 10 liters per mole of N-oxide.
liter of non-aqueous solvent.

[0025] Advantageously, the method of the invention is carried out from room temperature to 15
It is carried out at a temperature between 0° C., optionally under the natural pressure of the reactants.

The process of the invention also makes it possible to reuse the secondary amines produced by the conversion reaction with very good yields. In a particularly advantageous variant, the process according to the invention therefore comprises, after reacting the N-oxide of a tertiary amine with the vanadium derivative or derivatives, the aldehyde is recovered in the organic phase and the aldehyde is recovered in the aqueous phase. amine.

Furthermore, the new process makes it possible to prepare unsaturated aldehydes directly from conjugated dienes and secondary amines without isolating reaction intermediates.

Another subject of the invention is the following steps, without isolation of reaction intermediates: - in a first stage, condensing the conjugated diene with a secondary amine; - in a second stage, oxidizing the tertiary amine thus obtained with an oxidizing agent; and in a third step converting the N-oxide of the tertiary amine obtained into an unsaturated aldehyde using the method described above; A method for producing unsaturated aldehydes by carrying out the present invention.

This subject of the invention is an improved process for the synthesis of certain aldehydes, which is particularly well suited and effective for industrial applications.

The conjugated dienes that can be used in the process are preferably substituted or unsubstituted linear, branched or cyclic dienes having from 4 to 30 carbon atoms and optionally one or more heteroatoms. It is a conjugated diene. Advantageously, the conjugated dienes that can be used in the present invention are those that fall within the definition of the group R3 defined above.

Examples of conjugated dienes that can be used in the process of the invention include myrcene, isoprene, butadiene, farnesene and phytadiene.

The secondary amines used in the present invention preferably have the formula HNR1R2, where R1 and R2 may be the same or different and are as defined above. Examples include diethylamine, which gives good results.

The first step of the method of the invention can be carried out in various ways. Generally, the use of metal catalysts is preferred. In particular, the metals that can be used at this stage are alkali metals. Particular mention may be made of the metals sodium, lithium or potassium. More generally, Marata et al.
n Kagaku Kaishi, 1233, 198
The catalysts described under 2) are suitable for the process of the invention.

In particular embodiments, it is possible to carry out the reaction in the presence of an activator in order to increase the yield or rate. In particular, it is possible to add biphenyl or naphthalene to the alkali metal.

In a preferred embodiment of the invention, the amine/
The molar ratio of diene is between 0.1 and 5, preferably between 0.5 and 2. It is preferred to carry out the reaction in the presence of a slight excess of amine.

The reaction is advantageously carried out at a temperature between room temperature and reflux temperature. It is understood that reaction conditions (temperature, reaction time, ratio of reactants, etc.) are adapted by one skilled in the art according to the desired rate or yield.

Preferably the catalyst/diene molar ratio is 0.0
01 to 0.1.

Before carrying out the second step of the process of the invention, the alkali metal can be converted into the corresponding hydroxide or alkoxide by adding water or alcohol to the medium containing the alkali metal. may be suitable.

The second step consists in forming the N-oxide of the tertiary amine using an oxidizing agent.

Preferably, hydrogen peroxide is used as the oxidizing agent, optionally under a CO2 atmosphere or pressure. Advantageously, the amount of hydrogen peroxide is such that the hydrogen peroxide/conjugated double bond molar ratio approaches a stoichiometric ratio. It is furthermore advantageous to use a slight excess of hydrogen peroxide relative to the tertiary amine formed.

The oxidation reaction can optionally be carried out in the presence of a solvent, depending on the nature of the conjugated diene and amine used. In particular, it is possible to carry out this oxidation in an alcoholic medium (methanol) or in an organic acidic medium (acetic acid) or in the presence of acetone. Advantageously, solvents are used that are compatible with the final stage of the invention.

Other parameters of the reaction (temperature, time, etc.) are adapted by the person skilled in the art according to the diene and amine used and the desired reaction rate. Advantageously, the reaction temperature is between room temperature and 100°C.

The third step consists in converting the N-oxide of the tertiary amine formed in the previous step into an unsaturated aldehyde using a catalytic amount of one or more vanadium derivatives according to the method described above.

This method for the synthesis of aldehydes offers important advantages on an industrial level. In particular, the method of the invention is easy to carry out (uses a limited number of items of equipment, no need to handle intermediates, etc.) and provides time and economic benefits. Furthermore, the process of the invention makes it possible to regenerate the starting secondary amine in very good yields, which can be reacted again with the conjugated diene. Also, according to the invention, side reactions that occur with respect to reaction intermediates (e.g., in particular Meisenheimer, B.
er. 52, 1667 (1919)) is reduced, thereby increasing the yield of the process.

The invention will be more fully described in the following examples, which are to be understood to be illustrative and non-limiting.

[0046]

【Example】

Example 1 0.2 g of VOSO4 containing 22.75% vanadium was added to a 1 liter three-necked round bottom flask equipped with a stirrer, condenser, addition funnel and thermometer.
Add 80 mL of 0% acetic acid aqueous solution and 400 mL of methylene chloride.

The mixture is brought to reflux (38° C.) of methylene chloride while stirring. A 58% aqueous solution (13.6 g) of N,N-diethylgeranylamine N-oxide dissolved in 40 mL of methylene chloride was then poured in (addition time 11 minutes), and the funnel was then closed for 20 minutes.
Wash with mL of methylene chloride. pH is 4.1.

After heating this mixture to 38° C. for 1 hour,
Cool quickly to room temperature. After precipitation has taken place, the organic phase is separated and rapidly filtered through 250 g of active grade 4 alumina.

As a result of quantitative analysis of citral in this organic phase by gas chromatography, it was found that 7
Gives a yield of 5%.

Example 2 This example is conducted under the conditions described by Craig et al. Apart from implementation issues, the low efficiency of this method is explained.

Into a 3 liter, 3 neck round bottom flask equipped with a stirrer, condenser, addition funnel and thermometer are placed 2.04 liters of water and 7.59 g of VOSO4.5H2O.

The mixture is heated to 80° C. with stirring and 3.95 g of the 58% strength N,N-diethylgeranylamine N-oxide solution used in the previous example is added. pH is 2.4. This mixture was heated to 80℃ for 4 hours.
After heating for 0 minutes, cool and extract with 3 x 100 mL of methylene chloride. Quantitative analysis of citral in the organic phase as in Example 1 gives a yield of 2% citral. Geranic acid is not detected.

Example 3 This example illustrates the potential for recovery of secondary amines when using the method of the present invention.

N,N-diethylgeranylamine N-oxide at a concentration of 67.7% in aqueous solution was added to a 1 liter, 3-neck round bottom flask equipped with a stirrer, condenser, addition funnel and thermometer. Add 13.8g VOSO4.5H2O 0.2g 10% acetic acid aqueous solution 50mL and pentane 100mL.

The mixture is heated to reflux (33° C.) for 16 hours. After cooling and precipitation, separate and extract the aqueous layer with 2×50 mL of pentane. After concentration, 5.5
g of crude product is obtained, which is analyzed for citral. Yield is 48.8%. This crude product is distilled into 2
．． 8 g of citral (45% yield) are obtained.

[0056] Sodium hydroxide was added to this aqueous layer to adjust the pH.
10 and heating to 100 DEG C. with distillation, whereby 1.9 g of diethylamine can be recovered, corresponding to a yield of 64% based on the introduced N-oxide.

Example 4 A reaction vessel is charged with 7.5 mL of 10% acetic acid, 3.39 g of diethylgeranylamine N-oxide, 25 mL of pentane and an internal standard (by which the yield of aldehyde formed can be checked at any time). . 5 mL of 10% acetic acid
After dissolving 0.05g of VOSO4.5H2O in it,
This solution was poured into the reaction tank for 2 hours while maintaining the temperature at 35°C.
Pour over 5 minutes. Next, the production of citral over time is monitored by gas chromatography.

TY=actual yield=number of moles produced relative to number of moles introduced.

Time (minutes) 37 75 120
240 300 360 420
450 480 TY (%) 1.6
8 14.3 39.9 41.9 47
．． 4 52.6 54.3 55.3 Example 5 Equipped with condenser, thermometer and stirrer and N-
50mL with septum for introducing oxide
The reaction is carried out in a round bottom flask.

4×10 −5 mol of VOSO4 (calculated as metal) and an internal standard (C11 hydrocarbon) (by which the yield of the aldehyde formed can be checked at any time)
Put in. Then 4 ml of 10% acetic acid and 20 ml of chlorobenzene are introduced and the temperature is adjusted to 60°C. 3m
2x10-3 mol N diluted in L chlorobenzene
, N-diethylgeranylamine N-oxide is added to the flask, and the actual yield of citral is analyzed by gas chromatography. The pH of this reaction is 4-4.5.

The yield of citral is 46% in 45 minutes.

Example 6 The procedure was the same as in Example 5 except that NH4VO3 was used instead of VOSO4. The yield of citral is 9
It is 45% after 0 minutes.

Example 7 The procedure was the same as in Example 5 except that the reaction was carried out in the presence of acetylacetone vanadyl instead of VOSO4. The yield of citral obtained is 48% after 18 minutes. Example 8
The procedure was the same as in Example 5 except that VOSO4 was replaced by octadecyl orthovanadate. The yield of citral obtained is 42% in 45 minutes.

Example 9 The procedure was the same as in Example 5 except that triethanolamine orthovanadate was used instead of VOSO4. The yield of citral obtained is 32% in 90 minutes.

Example 10 The procedure was the same as in Example 5 except that the reaction was carried out in the presence of V2O5 instead of VOSO4. The yield of citral obtained is 33% in 220 minutes.

Example 11 4x10-6, 4x10-5 (Example 2) or 4x1
The procedure is similar to Example 5, except in the presence of 0-4 mol of VOSO4 (calculated as metal). The measured yield of citral is as follows:
TY time
(%) (minutes)
4x10-6 4x10-5 4x10
-4 15
45
30 2.5
45 345 32 When reducing the amount of catalyst, a decrease in the reaction rate is also observed, but the actual yield of citral is not affected.

Example 12 The procedure was the same as in Example 5, except that the reaction was carried out in the presence of methylene chloride instead of chlorobenzene and at a temperature of 37°C. The yield of citral obtained under these conditions is 61% after 55 minutes.

Example 13 The procedure is similar to Example 5, except that it is carried out at a temperature of about 45° C. in the presence of a 10:1 (vol/vol) hexane/chlorobenzene mixture as solvent. Under these conditions, the yield of citral is 45% after 4 hours.

Example 14 The procedure is similar to Example 5, except that it is carried out for 21 hours at a temperature of 30° C. in the presence of a 10:1 (vol/vol) pentane/methylene chloride mixture. Under these conditions, the yield of citral is 61%.

Example 15 In the presence of methanol, ethyl acetate or toluene, approx.
The operation was the same as in Example 5 except that it was carried out at a temperature of 0°C. The yield obtained is as follows.

In methanol: 18% citral in 1 hour In toluene: 43% citral AcOE in 1 hour
In t: 38% citral in 4 hours.

Example 16 The procedure is the same as in Example 5, except that it is carried out in the presence of tert-butyl methyl ether at a temperature of 50°C. The yield obtained is 43% in 2 hours.

Example 17 The procedure was the same as in Example 5 except that it was carried out in the presence of sulfuric acid. The pH of the reaction medium is adjusted to a value of 4.5-5. The yield obtained is 32% citral after 3 hours.

Example 18 The operation is the same as in Example 5. Pour the following three solutions in parallel: 2.025 g of N,N-diethylgeranylamine N-oxide aqueous solution with a concentration of 67% VOSO4 (containing 22.75% vanadium) 30.
8 mg Benzoic acid 2.57 g Water 12 mL Methylene chloride 69 mL Undecane (internal standard) 314 mg.

The pH itself is approximately 5.

Yield of citral after 1 hour at 38°C: 6
3%.

0.682 g of N,N-diethylgeranylamine N-oxide aqueous solution with a concentration of 67% VOSO4 (
22.75% vanadium) 10.6 mg Formic acid 0.322 g Water 4 mL Methylene chloride 23 mL Undecane (internal standard) 102 mg.

The pH itself is about 2.1-3.

Yield of citral after 22 hours at 38°C:
62%.

0.691 g of N,N-diethylgeranylamine N-oxide aqueous solution with a concentration of 67% VOSO4 (
22.75% vanadium) 10.7 mg tartaric acid 0.661 mg water 4 mL methylene chloride 33 mL undecane (internal standard) 118 mg.

The pH itself is about 2.4.

Yield of citral after 4 hours at 38°C: 6
1%.

Example 19 The procedure was the same as in Example 5 except that it was carried out in the presence of an organic acid and an inorganic acid. For this purpose, the second acid: 0.5
The apparatus is equipped with a device for injecting M HCl solution at a flow rate of 0.7 mL/hr. Add the following: 0.687 g of an aqueous solution of N,N-diethylgeranylamine N-oxide with a concentration of 67% 10.5 mg of VOSO4 0.12 g of acetic acid 4 mL of water 23 mL of methylene chloride.

After heating this mixture to 38°C, 0.5
Inject 2.1 mL of M HCl solution over 90 minutes. p
Maintain H between 4.2 and 4.5. After 4 hours and 40 minutes, the yield of citral is 60%.

Example 20 The procedure is the same as in Example 19. Insert the following:
0.675 g of N,N-diethylgeranylamine N-oxide aqueous solution with a concentration of 67% VOSO4 10.5 mg Crotonic acid 87.6 mg Water 4 mL Methylene chloride 23 mL.

After heating this mixture to 38°C, 0.5
Inject 2.3 mL of M HCl solution over 180 minutes. Maintain pH between 4.5 and 5. After 3 hours and 30 minutes, the yield of citral is 51%.

Example 21 The procedure is similar to Example 5, except that a 10:1 (vol/vol) pentane/methylene chloride mixture is used as the solvent and NH4VO3 is used as the catalyst and at a temperature of 30°C. Citral is obtained after 90 minutes with a yield of 50%.

Example 22 This example illustrates the possibility of using a catalyst derived from vanadium on a support.

This operation is the same as in Example 5. Add the following: 0.68 g of an aqueous solution of N,N-diethylgeranylamine N-oxide at a concentration of 67% 117 mg of 3% V2O5 on SiO2 0.42 acetic acid
6g water 4mL methylene chloride 23mL.

[0090] This mixture is heated to 37°C. The yield of citral is 60% after 3 hours.

Example 23 This operation is the same as in Example 22. Add the following: 0.68 g aqueous solution of N,N-diethylgeranylamine N-oxide at a concentration of 67% 36.9 mg V2O5 at 10% on alumina 0.4 acetic acid
32g water 4mL methylene chloride 23mL.

[0092] This mixture is heated to 37°C. The yield of citral is 60% after 3 hours.

Example 24 This operation is the same as in Example 5. Charge the following: 2.67 g of an aqueous solution containing 1.51 g of N,N-dimethylbenzylamine N-oxide 25 mL of chlorobenzene 12.5 mL of water containing 10% acetic acid 0.5 g of undecane, and 0.5 g of vanadyl sulfate. 05g (22.75% vanadium content).

After heating the mixture to reflux at 89°C,
Monitor progress with gas chromatography. After 15 minutes, the yield of benzaldehyde present in the organic layer is 63%. 13
After stopping the reaction after 5 minutes and extracting the aqueous layer with 2x15 mL of chlorobenzene, benzaldehyde is obtained with a yield of 69%.

Example 25 This operation is the same as in Example 5. Charge: 2.7 g of an aqueous solution containing 1.33 g of N,N-diethylprenylamine N-oxide, 4.8 mL of water, 1.2 mL of acetic acid, and 49 mg of vanadyl sulfate (containing 22.75% vanadium).

The mixture is heated to reflux at 62° C. for 4 hours. After cooling, precipitation occurs and is separated, the aqueous layer is saturated with NaCl and the product is extracted with 2x25 mL of hexane. Gas chromatography analysis of the prenal by combining the hexane phases gives a yield of 65% based on N-oxide.

Example 26 Charge the reaction vessel in the following order: 4.4 g VO of an aqueous solution containing 15 mmol of N,N-dimethyl-ortho-hydroxybenzylamine N-oxide.
SO4 0.002 eq. acetic acid 1.1 eq., and ethyl acetate 20 mL.

The mixture is heated to 60° C. for 5 hours and, after cooling, the aldehyde formed is analyzed by GC. An actual yield of 26% is obtained.

Example 27 A 50 mL reaction vessel equipped with a condenser, thermometer, pH meter electrode, and stirrer is charged with the following: 500 mg undecane (internal standard) 23.5 mg NH4VO3 0.3 g acetic acid 4 mL water Hexane 20mL.

After heating this mixture to 60°C, 3.3
Add 8 g of N,N-diethylgeranylamine N-oxide and 5 mL of hexane. After 6 minutes, the pH is about 4.
．． 1 using a syringe driver to hold the
Begin the introduction of N sulfuric acid (flow rate 1.7 mL/hr). After 2 hours and 40 minutes, a volume of 4.6 mL of 1N sulfuric acid has been introduced and the yield of citral is 45%.

Example 28 The procedure is the same as in Example 26. Insert the following:
Undecane 112 mg VOSO4 10.5 mg Crotonic acid 87.6 mg Water 4 mL Methylene chloride 20 mL.

After heating this mixture to 38°C, 675
Add mg of N,N-diethylgeranylamine N-oxide and 3 mL of methylene chloride. After 2 minutes, begin introducing 0.5 M hydrochloric acid (flow rate 1.7 mL/hr) using a syringe driver to maintain the pH at approximately 4.5. After 3 hours and 30 minutes, a volume of 2.3 mL of 1N sulfuric acid has been introduced and the yield of citral is 51%.

Example 29 Into a 50 mL three-necked flask equipped with a condenser, thermometer, pH meter electrode, and stirrer, place the following: 506 mg of undecane (internal standard) 12 mg of NH4VO3 1.2 g of acetic acid 4 mL of water Hexane 20mL.

After heating this mixture to 60°C, 3.3
Add 7 g of N,N-diethylgeranylamine N-oxide and 5 mL of hexane. This mixture is then heated for 1 hour.

After cooling, the organic phase is removed and, after evaporation, analyzed to determine its citral content.

The following is introduced into the aqueous phase: undecane, N-oxide (same amount as above) and a supplementary amount of acetic acid (0.6 g). The mixture is then heated for 1 hour, after which the further operations are the same as before. Nine conversions in this process are carried out on the same catalyst underlayer. The yield of citral is shown in the table below:

[0107]

Table 1 Example 30 0.2 g (0.03 mol) of lithium metal and 20% of the total amount of diethylamine (1.23 mol) are placed in a round bottom flask. The reactor is heated to reflux for 1 hour. 9
A mixture of 143 g (1 mole) of 5% myrcene and the balance 72.4 g of diethylamine is poured into the reactor over a period of 1 hour. React under reflux for 5 hours. After cooling, add 5 g of water. Distillation (mercury pressure 27m at 70℃
m) to remove excess diethylamine, unreacted myrcene and water. 176.7 g of residue was obtained,
This is placed under a CO2 atmosphere. 3 for 2 hours at 60℃
Add 100 g of 0% hydrogen peroxide. The mixture is left at this temperature for 2 hours. 271 g of crude N-oxide are thereby obtained. Using this 271 g of N-oxide, 320 g of water, 168 g of acetic acid (2.8 mol), 1
．． The conversion reaction is carried out by adding 88 g (0.016 mol) ammonium vanadate and 2000 mL hexane. The reaction mixture is heated to 60° C. for 30 minutes. After cooling and precipitation, the organic phase is separated off. Citral is analyzed by GC using the internal standard method. 64.6 g (0.42 mol) of citral were obtained, corresponding to a yield of 42% based on myrcene.

The intermediate yields are shown in the table below:

010
9]

[Table 2] Number of moles
Stage TY TY/Myrcene Myrcene
1-
- DEGA
0.79 79% 79
% N-oxide 0.68 86%
68% citral
0.42 62% 4
2% TY=actual yield DEGA=diethylgeranylamine The features and embodiments of the present invention are as follows.

1. contacting the N-oxide with a catalytic amount of one or more vanadium derivatives,
A method for converting N-oxides of tertiary amines into aldehydes.

2. The N-oxide of the tertiary amine has the general formula:

[0112]

[Chemical formula 3]

[In the formula, each of R1, R2 and R3 is
linear, branched or cyclic alkyl, alkenyl or benzyl groups, which may be the same or different and which may be substituted or unsubstituted and have up to 30 carbon atoms and optionally one or more heteroatoms; and R1 and R2 may be taken together to form a ring.

3. R1 and R2, which may be the same or different, each represent a linear or branched alkyl group having 1 to 4 carbon atoms, and together form a carbocyclic or heterocyclic ring; A good method according to item 2.

4. 4. The method according to claim 3, wherein R1 and R2 may be the same or different and each represents methyl or ethyl.

5. 2nd, 3rd or 4th, wherein R3 is a ring and/or a substituted or unsubstituted linear or branched allyl group having 3 to 30 carbon atoms, optionally having one or more heteroatoms; The method described in section.

6. 6. The method of claim 5, wherein R3 has 3 to 15 carbon atoms.

7. The amine N-oxide used is N,N-dialkylprenylamine N-oxide,
N,N-dialkylgeranylamine N-oxide, or N,N-dialkyl-(2,6,6-trimethyl-
1-cyclohexyl)methanamine N-oxide.

8. The amine N-oxide is N,N
-diethylgeranylamine N-oxide, N,N-diethylprenylamine N-oxide, or N,N-
8. The method according to claim 7, wherein the method is diethyl-(2,6,6-trimethyl-1-cyclohexyl)methanamine N-oxide.

9. 5. A method according to paragraphs 2, 3 or 4, wherein R3 is a substituted or unsubstituted benzyl group having up to 30 carbon atoms and optionally having one or more heteroatoms. 10. 10. A process according to claim 9, wherein the amine N-oxide used is a N,N-dialkylbenzylamine N-oxide.

11. The following steps are carried out without isolation of the reaction intermediates: - In the first step, the conjugated diene and the secondary amine are condensed; - In the second step, the tertiary amine thus obtained is treated with an oxidizing agent. and, in a third step, converting the resulting tertiary amine N-oxide to an unsaturated aldehyde by contacting it with a catalytic amount of one or more vanadium derivatives; 2. Process according to clause 1 for the production of saturated aldehydes.

12. The conjugated diene used is 4 to 3
12. The method according to claim 11, wherein the diene is a substituted or unsubstituted linear, branched or cyclic conjugated diene having 0 carbon atoms and optionally having one or more heteroatoms.

13. 13. The method of claim 12, wherein the conjugated diene is myrcene, isoprene, butadiene, farnesene or phytadiene.

14. The secondary amine used is of formula H
NR1R2 (wherein R1 and R2 are 3rd, 4th or 5th
11, 1 which is the same as defined in Section 1)
2 or 13.

15. 15. The method according to any one of clauses 11 to 14, wherein an alkali metal catalyst is used during the first step.

16. The amine/diene molar ratio is 0
．． 1-5. The method according to any one of items 11-15.

17. The first one in which the above ratio is between 0.5 and 2.
The method described in Section 6.

18. 18. A method according to any one of paragraphs 11 to 17, wherein the first step is carried out at a temperature between room temperature and reflux temperature.

19. 19. A method according to any one of paragraphs 11 to 18, wherein hydrogen peroxide is used as the oxidizing agent in the second stage.

20. The molar ratio of vanadium derivative (calculated as metal)/N-oxide is 0.0001 to 0.
．． 20. The method according to any one of items 1 to 19, wherein the method is 5.

21. 21. The method according to item 20, wherein the ratio is between 0.001 and 0.1.

[0132]22. 2. The method according to claim 1, wherein said contacting is carried out in the presence of a solvent.

23. The solvent is a hydrocarbon, an ether,
23. The method of claim 22, wherein the solvent is an ester, an alcohol, an aromatic solvent, a halogenated solvent or a mixture thereof.

24. The solvent is pentane, hexane,
23. The method of claim 22, wherein the ethyl acetate, methyl tert-butyl ether, chlorobenzene, methylene chloride, toluene, xylene, benzene or methanol.

25. The reaction medium contains 0.05 to 2 liters of water and 0 to 2 liters per mole of N-oxide.
No. 22--containing a volume of 0 liters of non-aqueous solvent
25. The method according to any one of Item 24.

[0136]26. The volume of the nonaqueous solvent is 0 to 10
26. The method according to paragraph 25, wherein the liter is liter.

[0137]27. A second step in which the aldehyde is recovered in an organic solvent and the secondary amine is recovered in an aqueous phase.
The method according to any one of items 2 to 26.

28. The first vanadium catalyst is a salt of vanadium in any possible oxidation state.
28. The method according to any one of items 27 to 27.

[0139]29. The vanadium catalyst is V2O5
, NH4VO3, alkyl vanadates such as triethanolamine orthovanadate (OVTEA) or octadecyl orthovanadate OV (OC18H3
7) 3. Acetylacetone vanadyl OV (AcAc)
29. The method according to any one of paragraphs 1 to 28, wherein Vanadyl sulfate VOSO4 or vanadyl sulfate VOSO4.

30. 30. A method according to any one of paragraphs 1 to 29, wherein the pH of the reaction medium is adjusted by adding an acid.

31. The third acid is a carboxylic acid.
The method described in item 0.

32. 32. A method according to paragraph 30 or 31, wherein the pH of the medium is maintained at a value between 4 and 7.

33. 33. A method according to any one of paragraphs 1 to 32, wherein the temperature is between room temperature and 150<0>C.

34. The method described in paragraph 1, essentially as described above.

35. Aldehydes produced by any of the methods listed in the preceding paragraph.

Claims (11)

[Claims] 1. A process for converting the N-oxide of a tertiary amine to an aldehyde, comprising contacting the N-oxide with a catalytic amount of one or more vanadium derivatives. 2. The N-oxide of the tertiary amine has the general formula: [Image Omitted] [In the formula, each of R1, R2 and R3 may be the same or different and represents a linear, branched or cyclic alkyl group. , an alkenyl or benzyl group, which may be substituted or unsubstituted and have up to 30 carbon atoms and optionally one or more heteroatoms, and R
The method according to claim 1, wherein 1 and R2 may be taken together to form a ring. 3. The following steps without isolation of reaction intermediates: - in a first step condensing the conjugated diene with a secondary amine; - in a second step condensing the tertiary amine thus obtained; oxidizing the tertiary amine with an oxidizing agent; and in a third step converting the resulting N-oxide of the tertiary amine to an unsaturated aldehyde by contacting it with a catalytic amount of one or more vanadium derivatives; 2. A method according to claim 1 for the production of unsaturated aldehydes. 4. The method according to claim 1, wherein the vanadium derivative (calculated as metal)/N-oxide molar ratio is from 0.0001 to 0.5. Claim 5: Claim 1, wherein the contact is carried out in the presence of a solvent.
Method described. 6. The vanadium catalyst is a salt of vanadium in any possible oxidation state.
5. The method according to any one of 5. 7. The vanadium catalyst is V2O5, NH
4VO3, alkyl vanadate such as triethanolamine orthovanadate (OVTEA) or octadecyl orthovanadate OV (OC18H37)3
, acetylacetone vanadyl OV (AcAc)2 or vanadyl sulfate VOSO4. 8. Process according to claim 1, characterized in that the pH of the reaction medium is adjusted by adding an acid. 9. A method according to claim 1, wherein the temperature is between room temperature and 150°C. 10. The method of claim 1 essentially as hereinbefore described. 11. An aldehyde produced by any of the methods described above.